I. Field
The following description relates generally to wireless communications and more particularly to selection of tones in communication networks.
II. Background
Wireless communication systems are widely deployed to provide various types of communication. For example, voice, data, video and so forth can be provided through wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources. For instance, a system may use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.
Wireless communication networks are commonly utilized to communicate information regardless of where a user is located (inside or outside a structure) and whether a user is stationary or moving (e.g., in a vehicle, walking). Generally, wireless communication networks are established through a mobile device communicating with a base station or access point. The access point covers a geographic range or cell and, as the mobile device is operated, the mobile device can be moved in and out of these geographic cells.
A network can also be constructed utilizing solely peer-to-peer devices without utilizing access points or the network can include both access points (infrastructure mode) and peer-to-peer devices. These types of networks are sometimes referred to as ad hoc networks. Ad hoc networks can be self-configuring whereby when a mobile device (or access point) receives communication from another mobile device, the other mobile device is added to the network. As mobile devices leave the area, they are dynamically removed from the network. Thus, the topography of the network can be constantly changing.
At times, some transmission links (e.g., communications between devices) might experience interference, which at times might be strong interference, from other transmission links. This interference can be caused by the random deployment that exists in ad hoc networks. For example, in a peer-to-peer ad hoc network, there is no central authority (e.g., base station) that transmits broadcast signals. Thus, synchronization is performed in an informal manner by the devices within the peer-to-peer network. Therefore, a problem with peer-to-peer ad hoc networks is interference.
In typical wide-area cellular wireless systems, the interference observed persists for a period of time and comes from several interferers with no single interferer being overly dominant. Aspects of the interferers make them appear as white Gaussian noise at a receiver, which can be accounted for by using techniques such as linear filtering. Increasingly deployed are ad hoc networks (e.g., hot-spots, home base stations, Femto cells, peer-to-peer, etc.), which facilitate direct device communication without consideration of whether there is a more optimal serving link as in typical wide-area cellular wireless deployments. Because more optimal serving links can exist without being utilized in the ad hoc deployments, there is a much greater likelihood of dominant interference from the more optimal serving link (or to the more optimal serving link).
Typically, in infrastructure networks, mobile devices search and connect to the best (from a radio link quality or load perspective) base station (also referred to as access point). However, in peer-to-peer or other applications, such as home base stations (also called Femto cells), a device connects directly to the device it desires to communicate with (peer-to-peer) or is allowed to communicate with (e.g. home base station/Femto cell scenario). This constraint, sometimes called restricted association, can give rise to much stronger interference than might be observed in conventional infrastructure-based cellular networks.